Ship stabilizer



S. B. FIELD ET SHIP STABILIZER Dec. 5, 1967 Original Filed March 30, 1965 4 Sheets-Sheet 1 mum &. I

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SHIP STABILIZER v Original Filed March 30, 1965 I 4 Sheets-Sheet 2 9' g? INVENTORS ATTORNEYS Jkeldozzfifz'elai Thomas E firz'dg'as' y Y WBMM/JM Dec. 5, 1967 s. B. FIELD ET AL SHIP STABILIZER 4 Sheets-Sheet 5 Original Filed March 30, 1965 fkelawz .5 Fz'eZcZ; Tlzamas E'Brz'dyes Mir/7 14 9m A ORNEYS Dec. 5, 1967 s. F|E| D ET AL 3,356,060

' SHIP STABILIZER Original Filed March 30, 1965 4 Sheets-Sheet 4 A/T'TORNEYS m 19m mam INVENTORS I J/zeZdanfl. Field, Thomas E'Bm'afyes United States Patent 0 Associates, Inc., New York, N.Y., a corporation of 5 New York ontinuation of application Ser. No. 443,951, Mar. 30, 1965. This appiication May 12, 1967, Ser. No. 638,154 9 Claims. (Cl. 114-125) ABSTRACT OF THE DISCLOSURE A passive tank stabilizer for a transversely framed ship which is formed at least in part by existing ship structure including a pair of transverse structural bulkheads spaced longitudinally apart and located between decks to form the tank and at least one longitudinal structural bulkhead extending through the tank and having a conventional vertical stiffening system thereon. Vertically elongated openings are cut in the longitudinal bulkhead and each opening extends above and below the static liquid level of the body of liquid partially filling the tank so that the tank generates a shallow water bore type transfer wave in response to the rolling of the ship.

This application is a continuation of application No. 443,951 filed Mar. 30, 1965, and now abandoned.

The present invention relates to passive ship stabilizers and, more particularly, to ship stabilizers for transversely framed vessels such as bulk cargo ships and the like.

There are two distinct systems of framing in common use that are distinguished from each other, and these systems are commonly known as transverse and longitudinal framing. The transverse system (see FIG. 1) is characterized by enlarged web frames 1 which extend down the sides of the vessel and across the bottom to the center keel. The longitudinal bulkheads 3 are generally mounted on the bottom of the vessel and extend vertically through the major portion of the hull. A plurality of stiffeners also extend down the sides and across the bottom of the hull and are transversely aligned with each other. Additional vertically arranged stiffeners 5 are mounted on the longitudinal bulkheads and are generally transversely aligned with the stilfeners on adjacent bulkheads and the stiffeners extending down the sides of the hull.

The term transverse framing stems from the fact that the framework of the entire hull is located in a plurality of transverse planes spaced from each other along the length of the ship. Another term for this system is deep framing due to the fact that the web frames run vertically through the hull and deep into the bottom thereof. There is normally spaced periodically throughout the vessel transverse bulkheads which function to add additional transverse rigidity to the structure.

The other type of framing used in ship construction is termed longitudinal framing (FIG. 2) and is characterized by a plurality of longitudinal girders 7 running parallel to the longitudinal axis of the vessel. These girders are spaced along the sides and bottom of the vessel. Again, the longitudinal bulkheads 9 are mounted from the fioor of the vessel vertically throughout a major portion of the hull. A plurality of longitudinal stifieners or stringers 11 are mounted along the sides of the hull and along the longitudinal bulkheads. These stringers are also preferably in the horizontal plane and run parallel to the longitudinal axis of the vessel. To add additional transverse rigidity to the vessel, a number of transverse webs 13 are mounted within the hull at selected spaced locations.

As pointed out in Design and Construction of Steel Merchant Ships (1955), the longitudinal framing system 3,356,660 Patented Dec. 5, 1967 lends itself well to liquid cargo vessels such as oil tankers and the like. My prior invention, now US. Patent No. 3,164,120, is drawn to incorporating a ship stabilizer into a tanker having longitudinal framing by using the existing ship structure and longitudinal framing to its utmost efiiciency. However, I have found that the concept expressed in this aforementioned United States Patent cannot be readily incorporated in a bulk cargo vessel or any type of vessel using transverse framing. The primary reason for this is that the longitudinal cuts or openings found in the bulkheads of United States Patent No. 3,164,120 cannot readily be made in the longitudinal bulkheads of a vessel having transverse framing because the cuts or openings would extend across existing vertical stiifeners normally found in ships of this type.

It is, therefore, a primary object of the present invention to solve the aforementioned problem and incorporate a passive stabilizer in a transversely framed vessel with the minimum amount of structural alteration and most efficient use of existing structure already found in the vessel.

Another object of the present invention is to incorporate a passive ship stabilizer in a transversely framed vessel which is positioned between two existing decks of the vessel.

Briefly stated, the present invention comprises modifying an already existing vessel having transverse framing or incorporating in a vessel being assembled two transverse liquid-tight plates extending from one side of the 30 hull to the other and vertically arranged between two existing decks thereof. With this arrangement, at least one longitudinal, structural bulkhead extends through the tank defined by the transversely extending plates. A plurality of vertical webs and stiifeners extend down the sides of the vessel and into the bottom thereof; these webs mesh with and are aligned with the central framework of the vessel. Moreover, existing vertical stiffeners on the longitudinal bulkheads also extend through the vessel, and preferably each is transversely aligned with other vertically arranged stiffeners on respective hull sides and bulkheads. A plurality of elongated vertically positioned" cuts or openings are cut into the longitudinal bulkhead between adjacent vertically arranged stilieners. The tank is then partially filled with liquid, and in response to the roll of the vessel, a portion of the liquid transfers through these openings wherein the kinetic energy of the transferring liquid is dissipated as the liquid passes therethrough. Due to the movement of liquid from one side of the vessel to the other, a stabilizing moment is imparted to the vessel.

A detailed description of the present invention will now .be made in view of the appended drawings, in which:

FIG. 7.

Referring now to FIGS. 3, 4, 5 and 6 in detail, there is shown generally a vessel 20 and a first deck 22 and a second deck or tank top 24 positioned over a double bottom with a keel 26 therebetween. In accordance with deep frame construction, the deep or transverse web frames 28 and the vertical stiffeners 30 extend down the sides of the hull and into the bottom framing. Longitudinal bulkheads 32 are oil-tight structural bulkheads and are mounted in the bottom of the hull and extend vertically throughout a major portion thereof. Wash plates 34, the function of which will be described hereinbelow, are also mounted at the bottom of the hull and extend to deck 22.

Vertical stilfeners 36 and 38 are mounted on bulkheads 32 and wash plates 34, respectively, and extend vertically to the bottom framework in the normal manner. These stitfeners 36 and 38 provides lateral rigidity for the respective bulkheads 32 and wash plates 34.

To form the stabilizer container, oil-tight plates 40 are mounted transversely in the vessel and extend vertically between decks 22 and 24. Preferably, one or both of these oil-tight plates 40 comprises transverse liquid-tight bulkheads already incorporated within the ships structure.

As better seen in FIG. 5, a plurality of vertically elongated cuts or openings 42 are made approximately centered in longitudinal bulkhead 32. Each longitudinal opening 42 has an upper and lower limit, and it is preferred, but not absolutely necessary, that the upper and lower limit of these openings be horizontally aligned. Each opening 42 is cut vertically between the vertically arranged stiifeners 36 so as not to lessen the function thereof and, at the same time, enable sufficient liquid transfer in a manner to be described below. Importantly, openings 42 do not seriously weaken the vertical support characteristics of bulkhead 32, which continues to function as a structural bulkhead.

Smaller cuts 44 are made preferably at the top of the longitudinal bulkhead 32 for the purpose of enabling unimpeded transfer of air which normally takes place when large volumes of liquid transfer across the tank.

semicircular openings 46 at the bottom of the longitudinal bulkhead enable optimum liquid transfer in the event the normal liquid level is substantially equal to the lower limit of openings 42. Thus, openings 46 provide efficient liquid transfer even though the magnitude of roll is very small.

It must be remembered that longitudinal bulkhead 32 is a structural bulkhead, and, consequently, the openings 42, 44 and 46 are preferably rounded so that the forces encountered do not create extreme stresses therein.

Wash plates 34 are located outside the outermost bulkheads 32 and also have openings 48, 50 and 52 cut therein. Wash plate 34 is not a structural bulkhead so that vertically elongated openings 48 are of a larger area, and preferably this area is approximately twice the area of openings 42 in structural bulkhead 32. The function of wash plate 34 is to prevent unwanted and unexpected surges within that portion of the tank positioned outboard of structural bulkhead 32.

After the installation of the described structure, a volume of any suitable liquid such as fuel oil, bunker oil, seawater, fresh water, or the like is introduced to partially fill the stabilizer.

The operation of the stabilizer is as follows. As the vessel rolls due to normally encountered forces from without, the liquid within the stabilizer transfers through the openings 42 and 46 from the high side to the low side of the vessel. As the liquid passes through the openings 42, kinetic energy is dissipated therefrom due to the pressure drop experienced thereat. The liquid, therefore, accumulates at the lower side of the vessel so that a moment is developed in opposition to the next portion of the cycle of roll of the vessel. In this way, the stabilizer imparts a stabilizing moment as long as the vessel continues to roll.

Since the space taken for the stabilizer is usually not easily used for the storage of bulk cargo, it is preferred that the stabilizer be in as low a location in the vessel as possible. Another advantage of the present invention is that an entire deck height can be used for the stabilizer, if necessary, and the stabilizer is not confined to the double bottom of the vessel as found in some prior systems. See, for example, the patent to Carroll, US. Patent No. 2,077,143.

FIGS. 7 and 8 illustrate another embodiment of the present invention. It should be understood that like characters refer to like structure. FIG. 7 is a plan view of a tank in a transversely framed vessel which has three structural longitudinal bulkheads 32 extending therethrough. Transverse liquid-tight plates 60 and 62 are mounted between two decks 22 and 24 of the vessel and cooperate with the sides of the vessel to define an enclosed tank stabilizer generally indicated as 64. As seen in FIG. 7, the dimension of the tank 64 between the outermost bulkheads 32 is somewhat narrower than the wing tanks defined between outer-most bulkheads 32 and its respective side of the vessel. Verticalliy elongated openings 42' extend throughout a major portion of bulkheads 32, and each opening 42' is located between vertical stiffeners 36. The outermost openings 42' have a reinforcing member 66 mounted at the outside thereof to reinforce the supporting function of the bulkhead.

Openings 42' extend throughout the major vertical dimension of bulkheads 32 in this embodiment to insure sufficient liquid transfer therethrough and to avoid the necessity of incorporating air openings at the top of the bulkhead. This feature enables fewer cuts to be made in the bulkhead during the assembling of the stabilizer so that quicker and less expensive installation of the stabilizer can be made.

The operation of this embodiment of the present invention is the same or similar to that for the embodiment described in the FIGS. 3-6 except that all liquid and air transfer occurs through openings 42.

It should be understood that other and further modifications of the present invention can be made without departing from the spirit and scope of the present invention. It should also be understood that the present invention can be used in vessels having any degree of transverse framing. Therefore, vessels having a combination transverse-longitudinal frame system are also adapted to include a stabilizer comprising the present invention.

What is claimed is:

1. A vessel comprising a hull, a deep framing system including a plurality of web frames spaced longitudinally from each other and arranged in vertical planes transverse to the hull, said web frames running down the sides and across the bottom of the hull, a passive tank stabilizer comprising two spaced liquid-tight plates arranged vertically between two decks and extending from one side of the vessel to the other, and defining with the sides of the vessel an elongated enclosed tank having its long dimension mounted transversely to the roll axis of the vessel one of said decks being arranged between the main deck and the inside hull bottom, at least one upstanding, longitudinal structural bulkhead connected between said two transverse plates, a plurality of elongated openings defined in said longitudinal bulkhead having their greater dimension positioned vertically, and a body of liquid partially filling said tank to a level tuning the tank liquid oscillation with the ship roll and so as to generate a transfer wave rather than a standing wave, each of said openings extending above and below the static level of the liquid body and dissipating kinetic energy from the portion of liquid transferring therethrough in response to the roll of the vessel.

2. The vessel as set forth in claim 1 wherein said openings are spaced from each other and said framing system further comprising a plurality of bulkhead stiffeners secured vertically to the solid parts of said longitudinal bulkhead between said openings.

3. The vessel as set forth in claim 2 wherein said framing system comprises a plurality of side stiffeners running down the sides of the vessel and at least some of said side stiffeners and web frames being in the same transverse plane as said bulkhead stiffeners so that the bulkhead stiffeners are aligned with the over-all transverse framing system of the vessel.

4, The vessel as set forth in claim 3 wherein at least one 5 of said transverse plates comprises a transverse structural bulkhead.

5. The vessel as set forth in claim 4 wherein said vessel comprises at least two longitudinal bulkheads with openings therein and said openings being arranged so that the upper and lower limits thereof are aligned, said longitudinal bulkheads further defining a plurality of smaller openings above said plurality of openings substantially at the top of the tank.

6. The vessel as set forth in claim 5 wherein said stabilizer further comprises a swash bulkhead positioned parallel to and outboard of each outermost longitudinal bulkhead, said swash bulkhead defining openings each of about twice the area of each opening of the longitudinal bulkhead, a vertical stiffener secured to the solid parts between openings of said swash bulkhead and transversely aligned with a stiflener of said longitudinal bulkhead, said swash bulkhead, openings having their upper and lower limits aligned and said swash bulkheads defining additional openings above and below said first mentioned swash bulkhead openings near the top and bottom of said swash bulkheads, respectively.

7. The vessel as set forth in claim 2 wherein said vessel comprises at least two longitudinal bulkheads with each defining vertical bulkhead openings forming two outer wing tanks and a central interconnecting tank, each said wing tank having a greater dimension in the vessels longitudinal direction than the interconnecting channel, said vertical bulkhead openings extending substantially from bottom to top of the tank,

8. The vessel as set forth in claim 7 wherein each said longitudinal bulkhead further comprises a vertical reinforcement member positioned vertically along the outermost edges of said bulkhead openings.

9. The vessel of claim 1 comprising an additional plurality of openings formed in each longitudinal bulkhead each in general vertical alignment with one of said elongated openings and being spaced therebelow, said additional openings being formed generally at the location where the longitudinal bulkhead meets the deck forming the bottom of tank, said additional openings permitting damped major liquid transfer whenever said liquid level operates at the more shallow set-tings.

References Cited UNITED STATES PATENTS 1/1965 Field 1l4125 7/1966 Hilliard 114-125 

1. A VESSEL COMPRISING A HULL, A DEEP FRAMING SYSTEM INCLUDING A PLURALITY OF WEB FRAMES SPACED LONGITUDINALLY FROM EACH OTHER AND ARRANGED IN VERTICAL PLANES TRANSVERSE TO THE HULL, SAID WEB FRAMES RUNNING DOWN THE SIDES AND ACROSS THE BOTTOM OF THE HULL, A PASSIVE TANK STABILIZER COMPRISING TWO SPACED LIQUID-TIGHT PLATES ARRANGED VERTICALLY BETWEEN TWO DECKS AND EXTENDING FROM ONE SIDE OF THE VESSEL TO THE OTHER, AND DEFINING WITH THE SIDES OF THE VESSEL AN ELONGATED ENCLOSED TANK HAVING ITS LONG DIMENSION MOUNTED TRANSVERSELY TO THE ROLL AXIS OF THE VESSEL ONE OF SAID DECKS BEING ARRANGED BETWEEN THE MAIN DECK AND THE INSIDE HULL BOTTOM, AT LEAST ONE UPSTANDING, LONGITUDINAL STRUCTURAL BULKHEAD CONNECTED BETWEEN SAID TWO TRANSVERSE PLATES, A PLURALITY OF ELONGATED OPENINGS DEFINED IN SAID LONGITUDINAL BULKHEAD HAVING THEIR GREATER DIMENSION POSITIONED VERTICALLY, AND A BODY OF LIQUID PARTIALLY FILLING SAID TANK TO A LEVEL TUNING THE TANK LIQUID OSCILLATION WITH THE SHIP ROLL AND SO AS TO GENERATE A TRANSFER WAVE RATHER THAN A STANDING WAVE, EACH OF SAID OPENINGS EXTENDING ABOVE AND BELOW THE STATIC LEVEL OF THE LIQUID BODY AND DISSIPATING KINETIC ENERGY FROM THE PORTION OF LIQUID TRANSFERRING THERETHROUGH IN RESPONSE TO THE ROLL OF THE VESSEL. 